Apparatus for grinding gear teeth



March 10, 194-2. PARZ 2,275,804

APPARATUS FOR; GRINDING GEAR TEETH Filed June 14, 1939 3 Sheets-Sheet l March 10, 1942. E. PARZ APPARATUS FOR GRINDING GEAR TEETH I Filed June 14, 1939 3 Sheets-Sheet 2 meg/:5.

m. f I 2 March 10, 1942. E. PARZ 2,275,804

APPARATUS FOR GRINDING GEAR TEETH Filed June 14, 1939 3 Sheets-Sheet 3 Vane/mar 5.27 Quiz- 0 Patented Mar. 10, 1942 APPARATUS FOR GRINDING GEAR TEETH Erich Pars, Karlshorst, near Berlin, Germany,

assignor to Deutsche Niles Werke Aktiengesellschaft, Weissensee, near Berlin, Germany Application June 14, 1939, Serial -No. 279,230

In Germany June 21, 1938 4 Claims.

This invention relates to mechanisms intended especially for machines for grinding or polishing involute gear teeth of the type in which the rolling movement between the work-piece and the tool is not uniform.

If, when an involute gear tooth is produced, the rolling velocity of grinding is kept constant, there are produced difierently large longitudinal sections of the involute in the same period of time. The longitudinal sections become larger are rotatably supported on the slide 2, and conwhen the distance from the rolling circle increases and the tooth flanks are not ground accurately. It has for this reason become necessary toadjust the rolling velocity during the grinding operation in such a manner that the tooth heads are ground satisfactorily which entails, however, the drawback that the tooth flank portions lying in the proximity of the rolling circle are being ground too slowly, or uneconomically.

In machines with two grinding disks for abrading involute gear teeth it is known togive said disks a variable rolling movement relatively to the tooth profile in such a manner that the disks act on approximately equal profile lengths per unit of time. In order to attain this particular rolling movement cams are used in these machines.

An object of the present invention is to provide a device which renders possible alterations of the rolling movement of the work-piece relatively to the tool bysimple means, without the employment of expensive cams.

The chief characteristic feature of the invention is that for theproduction of irregular rolling movement a slot and crank device is provided. the appertaining crank of which performs a uniform reciprocating motion.

Changes in the rolling movement can be obtained, according to this invention, by adjusting the point where the oscillating arm engages a slide acting on the work-piece carrier.

The invention is illustrated diagrammatically and by way of example in the accompanying drawings in which Figure 1 is a plan of one constructional form designed according to this invention. Figure 2 is a similar representation showing another constructional form, and Figure 3 is a similar representation showing a third constructional form, all as fully described hereinafter.

Referring to Fig. 1, i denotes a base frame provided with guide members 3 on which a slide 2 can be reciprocated. 0n the slide 2 is a supporting member 4 for the work-piece to be dealt with which is, in the example shown, a gear wheel 1'. The carrier 4 with the gear wheel 1' nected with the carrier 4 is, in the example shown, a disk 5 around which a band 5 extends, the ends of which are aihxed to the frame I of the machine.

Moving theslide 2 to and fro, together with the parts its carries, relatively to a grinding disk I which is moved up and down in the direction of the teeth gap and is shaped at its rimlike a rack tooth,.is effected by means of the following mechanism:

- In the frame of the machine is supported on a pivot 9 an upwardly; extending arm 8 having a slot l0 engaged by a pin ll projecting from a female screw l2 supported upon a threaded spindle l3. This spindle is uniformly turned alternately in one and in the other direction, where by the arm 8 is oscillated correspondingly by the members II and I2. The arm 8 is provided with a pin ll engaging a slot l5 of a horizontal lever it connected with the slide 2.

In the position shown in Fig. l the slotted arm 8 is in' its middle position in which the pivot I4 is located at the point 5. The circular curve represents the path of said pivot and is provided with the numerals 0 to 10. It will be noted that the female screw l2 hasbeen movedwith uniform velocity from the position corresponding to the numeral 0 on the spindle l3 to the position corresponding to the numeral 5 thereof. The movement of the pin I4 is transmitted to the lever It, as well as to the slide 2 with which it is connected, by the slot ii of the first-mentioned slide, but owing to the pin H moving througha curved path the movement of the slides l6 and- 2 is not uniform, but unequally accelerated .and

,moved to an extent corresponding to thedistance between the points 0 and 5, and thus the gear wheel 1' is turned with unequal velocity in the distance between the points 0 and 5, shown on the generating circle-b. The tangents drawn through all "said points 0 to1'5show that while the unequal rolling movement of the wheel 1' is effected the grinding disk ,1 will have acted on nearly equal profile sections of the tooth flank a during equal periods of time in which the threaded spindle I3 is uniformly turned.

While the female screw I2 is further moved 7 to the right by the spindle l3 so as to pass the points 6 to 10 the rotary motion of the wheel r is unequally retarded so that during this time the grinding disk I has likewise acted on nearly equal profile sections of the tooth flank a I wish it to be understood that I do not limit my invention to constructional forms in which both tooth flanks are ground during one rolling stroke. It is quite possible to vary the construction in such a manner that only one flank is acted on by the grinding disk during one rolling stroke.

In the modification shown in Fig. 2 the arm 8 is moved in such a manner that it moves with constant angular speed on the circularly curved path 0 to 10. For the rest, the construction is the same as in Fig. 1.

In both forms of construction according to Figs. 1 and 2 the bea"ng bracket II of the pivot 9 and the pin ll of levers O and respectively are adjustably. \ounted, in order to change the ratio of movements.

In the modification illustrated in Fig. 3 the arrangement of the parts is such that the rolling movement varies with respect to the arrangements shown in Figs. 1 and 2, the object being in this case to grind the head portion of the tooth flank more slowly than the foot portion.

The threaded spindle is is also in this case turned with uniform speed so that the nut l2 covers equally long paths in .equally long periods of time. The intermediate members transmitting the motion from the spindle l! to gear r provide an unequal rolling movement of the gear wheel.

The tangents extending through the points 0 to 5 of the generating circle b show that unequal arranged for generating" gear teeth on the gear carried by said am engaging said lever within said slot, and means for swinging said arm.

2. In apparatus for generating gear teeth, a frame, ,a member slidable on the frame, a gear blank rotatably mounted onsaid member, means for rotating the gear blank during sliding movement of said member, a disc-shaped cutting tool blank, a longitudinally movable lever connected to said slide member, said lever having a transverse slot therein, a pivotally mounted arm, a pin carried by, said arm engaging said lever within said slot, means for swinging said arm,

rolling motion of the wheel 1' takes place during equal periods of time in which the uniform driving movement of the nut It continues along the path 0. to 5 and the abrasive disk 1 thus grinds smaller profile sections on the head of the tooth than'on. the footportion of the tooth. When the nut I2 is further moved (to the right) along the path 5 to 10 the movement of the wheel- 1- is unequally retarded, and it appears from thetangents on the points 5 to 10 of the generating circle I) that the grinding disk 1 acts also during this part of the rolling path on smaller profile sections on the head portion of the tooth fiank a than on the foot portion of the tooth flank a during the the same interval of time.-

vI claim:

1. In apparatus for generating involute gear teeth of gear wheels, a frame, a member slidable on the'frame, a gear blank rotatably mounted on said slide member, a disc rotatable with the gear blank, 3, band extending around said disc with the ends'thereof fixed with respect to the frame, a disc-shaped cutting tool arranged for generating gear teeth on the gear blank, a longiand means movable transversely of the movement of said lever for adjusting the pivoting position of said arm on said frame.

3. In apparatus for generatinginvolute gear teeth of gear wheels, 9. frame, a member slidable on the frame, a gear blank rotatably mountedon said slide member, a disc rotatable with the gear blank, a band extending around said a disc with the ends thereof fixed with respectto the frame, a disc-shaped cutting tool arranged for generating gear teeth on the gear blank, a longitudinally movable lever connected to. the slidable member extending therefrom in the direction of movement of the slide member, said lever having a transverse slot therein, a pivotally mounted arm arranged transversely of said lever, a pin carried by said arm engaging said lever within said slot, and a threaded spindle arranged substantially parallel with respect to said lever for swinging said arm.

4. In apparatus for generating gear teeth, a

frame, a member slidable on the frame, a gear blank rotatably mounted on said member, means for rotating the gear blank during sliding movement of said member, a disc-shaped cutting tool arranged for generating gear teeth on the gear blank, a longitudinally movable lever connected to said slide member, said lever having a transverse slot therein, a pivotally mounted arm, a pin carried by said arm engaging said lever within said slot, said arm having a longitudinally extending slot therein, a threaded spindle arranged transversely of said arm, a nut member threaded on said spindle, and a pin carried by said nut member engaging said arm within the slot thereof.

ERICH PARZ. 

